1. Technical Field
Several aspects of the present invention relate to an organic electroluminescence device having a plurality of organic electroluminescence (hereafter referred to as “EL”) elements formed on a substrate, the manufacturing method thereof, and an electronic apparatus including the organic EL device.
2. Related Art
The organic EL device includes, as its main components a circuit element substrate and organic EL elements. This circuit element substrate includes a substrate such as glass substrates, wirings formed thereon, and pixel circuits connected to those wirings. Those wirings include, for instance, a plurality of scanning lines, and a plurality of signal lines and power lines that are aligned to cross these scanning lines. Here, the power lines supply electric power to the organic EL elements. The pixel circuits are arranged at the crossing points of the scanning lines and the signal lines. Each pixel circuit functions in a manner that the organic EL element emits light by impressing a voltage between the power source and the electrode of the organic EL element (another or cathode). A transistor included in the pixel circuit is connected serially to the organic EL element at a location between the power source and the organic El, element. This transistor adjusts the current supplied to the organic EL element, thereby causing the organic EL element to emit light in a desired luminance.
In the above-referenced organic EL devices, storage capacitors that store the voltage applied to the transistors are commonly included in the pixel circuits. An example of the methods for forming such storage capacitors is disclosed in JP A-2002-189429. This example discloses a semiconductor device including: a substrate having a metallic surface; an insulation film formed on the substrate which has the metallic surface; a pixel unit formed on the insulation film; wherein the pixel unit includes thin film transistors (TFTs) and a wiring that connects the TFTs; and wherein a storage capacitor is formed including the insulation film the wiring, and the substrate having a metallic surface.
The above example also cites methods for increasing the storage capacitance, such as: making a thin insulation film that functions as dielectrics; and providing a large region (area) for forming the storage capacitance. However, the region in which the capacitor can be formed is limited to the area surrounded by the scanning line (gate wiring) and the signal line (source wirings). Therefore, the effective way to increase the capacitance is to make the thickness of the insulation film thin. On the other hand, a considerable parasitic capacitance is generated between the conductive substrate and the wirings when the thickness of the insulation film is small. In order to avoid an increase of a parasitic capacitance, it is desirable to thicken the insulation film that is provided between the substrate and the components such as wirings. Consequently, fulfilling the two contradicting requirements, which is to increase the storage capacitance and to decrease the parasitic capacitance, is difficult.